At the present state of the art the apparatus used in separating such frictional contact members as taper fit contacting surfaces and temperature differential insertion contacting surfaces usually involves high leverage mechanical stress with independent provision for transmission of hammer blows to the contacting parts. The use of hydraulic force in this type of application would have the advantage that large stresses can be achieved that when separation occurs does not result in excessive motion and the stress application portion of hydraulic apparatus can usually be remote from the pump giving physical size advantages in places with reduced clearance. Heretofore, in the art, however, there has been no provision in a single apparatus for both hydraulic stress and hammer shock forces in a single hydraulic separating device.